1. Field of the Invention
This invention relates to the field of medical devices, and more particularly to a system and method for locally delivering materials within the body of a patient. Still more particularly, it relates to a system and method for locally delivering interventional medical devices into branch body lumens from a main lumen, and in particular into renal arteries or veins extending from an abdominal aorta or vena cava, respectively, in a patient.
2. Description of Related Art
Many different medical device systems and methods have been previously disclosed for locally delivering fluids or other agents or materials into various body regions, including body lumens such as vessels, or other body spaces such as organs or heart chambers. Local “fluid” delivery systems may include drugs or other agents, or may even include locally delivering the body's own fluids, such as artificially enhanced blood transport (e.g. either entirely within the body such as directing or shunting blood from one place to another, or in extracorporeal modes such as via external blood pumps etc.). Local “agent” delivery systems are herein generally intended to relate to introduction of a material as an agent into the body, which may include drug or other useful or active agent, and may be in a fluid form such as liquid or gas, or other form such as gels, solids, powders, gases, etc. It is to be understood that reference to only one of the terms fluid, drug, or agent with respect to local delivery descriptions may be made variously in this disclosure for illustrative purposes, but is not generally intended to be exclusive or omissive of the others; they are to be considered interchangeable where appropriate according to one of ordinary skill unless specifically described to be otherwise.
In general, local agent delivery systems and methods are often used for the benefit of achieving relatively high, localized concentrations of agent where injected within the body in order to maximize the intended effects there and while minimizing unintended peripheral effects of the agent elsewhere in the body. Where a particular dose of a locally delivered agent may be efficacious for an intended local effect, the same dose systemically delivered would be substantially diluted throughout the body before reaching the same location. The agent's intended local effect is equally diluted and efficacy is compromised. Thus systemic agent delivery requires higher dosing to achieve the required localized dose for efficacy, often resulting in compromised safety due to for example systemic reactions or side effects of the agent as it is delivered and processed elsewhere throughout the body other than at the intended target.
Various diagnostic systems and procedures have been developed using local delivery of dye (e.g. radiopaque “contrast” agent) or other diagnostic agents, wherein an external monitoring system is able to gather important physiological information based upon the diagnostic agent's movement or assimilation in the body at the location of delivery and/or at other locations affected by the delivery site. Angiography is one such practice using a hollow, tubular angiography catheter for locally injecting radiopaque dye into a blood chamber or vessel, such as for example coronary arteries in the case of coronary angiography, or in a ventricle in the case of cardiac ventriculography.
Other systems and methods have been disclosed for locally delivering therapeutic agent into a particular body tissue within a patient via a body lumen. For example, angiographic catheters of the type just described above, and other similar tubular delivery catheters, have also been disclosed for use in locally injecting treatment agents through their delivery lumens into such body spaces within the body. More detailed examples of this type include local delivery of thrombolytic drugs such as TPA™, heparin, cumadin, or urokinase into areas of existing clot or thrombogenic implants or vascular injury. In addition, various balloon catheter systems have also been disclosed for local administration of therapeutic agents into target body lumens or spaces, and in particular associated with blood vessels. More specific previously disclosed of this type include balloons with porous or perforated walls that elute drug agents through the balloon wall and into surrounding tissue such as blood vessel walls. Yet further examples for localized delivery of therapeutic agents include various multiple balloon catheters that have spaced balloons that are inflated to engage a lumen or vessel wall in order to isolate the intermediate catheter region from in-flow or out-flow across the balloons. According to these examples, a fluid agent delivery system may be coupled to this intermediate region in order to fill the region with agent such as drug that provides an intended effect at the isolated region between the balloons.
The diagnosis or treatment of many different types of medical conditions associated with various different systems, organs, and tissues, may also benefit from the ability to locally deliver fluids or agents in a controlled manner. In particular, various conditions related to the renal system would benefit a great deal from an ability to locally deliver of therapeutic, prophylactic, or diagnostic agents into the renal arteries.
Acute renal failure (“ARF”) is an abrupt decrease in the kidney's ability to excrete waste from a patient's blood. This change in kidney function may be attributable to many causes. A traumatic event, such as hemorrhage, gastrointestinal fluid loss, or renal fluid loss without proper fluid replacement may cause the patient to go into ARF. Patients may also become vulnerable to ARF after receiving anesthesia, surgery, or α-adrenergic agonists because of related systemic or renal vasoconstriction. Additionally, systemic vasodilation caused by anaphylaxis, and anti-hypertensive drugs, sepsis or drug overdose may also cause ARF because the body's natural defense is to shut down, i.e., vasoconstriction of non-essential organs such as the kidneys. Reduced cardiac output caused by cardiogenic shock, congestive heart failure, pericardial tamponade or massive pulmonary embolism creates an excess of fluid in the body, which can exacerbate congestive heart failure. For example, a reduction in blood flow and blood pressure in the kidneys due to reduced cardiac output can in turn result in the retention of excess fluid in the patient's body, leading, for example, to pulmonary and systemic edema.
Previously known methods of treating ARF, or of treating acute renal insufficiency associated with congestive heart failure (“CHF”), involve administering drugs. Examples of such drugs that have been used for this purpose include, without limitation: vasodilators, including for example papavarine, fenoldopam mesylate, calcium channel blockers, atrial natriuretic peptide (ANP), acetylcholine, nifedipine, nitroglycerine, nitroprusside, adenosine, dopamine, and theophylline; antioxidants, such as for example acetylcysteine; and diuretics, such as for example mannitol, or furosemide. However, many of these drugs, when administered in systemic doses, have undesirable side effects. Additionally, many of these drugs would not be helpful in treating other causes of ARF. For example, a septic shock patient with profound systemic vasodilation often has concomitant severe renal vasoconstriction, administering vasodilators to dilate the renal artery to a patient suffering from systemic vasodilation would compound the vasodilation system wide. In addition, for patients with severe CHF (e.g., those awaiting heart transplant), mechanical methods, such as hemodialysis or left ventricular assist devices, may be implemented. Surgical device interventions, such as hemodialysis, however, generally have not been observed to be highly efficacious for long-term management of CHF. Such interventions would also not be appropriate for many patients with strong hearts suffering from ARF.
The renal system in many patients may also suffer from a particular fragility, or otherwise general exposure, to potentially harmful effects of other medical device interventions. For example, the kidneys as one of the body's main blood filtering tools may suffer damage from exposed to high-density radiopaque contrast dye, such as during coronary, cardiac, or neuro angiography procedures. One particularly harmful condition known as “radiocontrast nephropathy” or “RCN” is often observed during such procedures, wherein an acute impairment of renal function follows exposure to such radiographic contrast materials, typically resulting in a rise in serum creatinine levels of more than 25% above baseline, or an absolute rise of 0.5 mg/dl within 48 hours. Therefore, in addition to CHF, renal damage associated with RCN is also a frequently observed cause of ARF. In addition, the kidneys' function is directly related to cardiac output and related blood pressure into the renal system.
These physiological parameters, as in the case of CHF, may also be significantly compromised during a surgical intervention such as an angioplasty, coronary artery bypass, valve repair or replacement, or other cardiac interventional procedure. Therefore, the various drugs used to treat patients experiencing ARF associated with other conditions such as CHF have also been used to treat patients afflicted with ARF as a result of RCN. Such drugs would also provide substantial benefit for treating or preventing ARF associated with acutely compromised hemodynamics to the renal system, such as during surgical interventions.
There would be great advantage therefore from an ability to locally deliver such drugs into the renal arteries, in particular when delivered contemporaneous with surgical interventions, and in particular contemporaneous with radiocontrast dye delivery. However, many such procedures are done with medical device systems, such as using guiding catheters or angiography catheters having outer dimensions typically ranging between about 4 French to about 12 French, and ranging generally between about 6 French to about 8 French in the case of guide catheter systems for delivering angioplasty or stent devices into the coronary or neurovascular arteries (e.g. carotid arteries). These devices also are most typically delivered to their respective locations for use (e.g. coronary ostia) via a percutaneous, translumenal access in the femoral arteries and retrograde delivery upstream along the aorta past the region of the renal artery ostia. A Seldinger access technique to the femoral artery involves relatively controlled dilation of a puncture hole to minimize the size of the intruding window through the artery wall, and is a preferred method where the profiles of such delivery systems are sufficiently small. Otherwise, for larger systems a “cut-down” technique is used involving a larger, surgically made access window through the artery wall.
Accordingly, a local renal agent delivery system for contemporaneous use with other retrogradedly delivered medical device systems, such as of the types just described above, would beneficially allow for such interventional device systems, in particular of the types and dimensions just described, to pass upstream across the renal artery ostia (a) while the agent is being locally delivered into the renal arteries, and (b) while allowing blood to flow downstream across the renal artery ostia, and (c) in an overall cooperating system that allows for Seldinger femoral artery access. Each one of these features (a), (b), or (c), or any sub-combination thereof, would provide significant value to patient treatment; a local renal delivery system providing for the combination of all three features is so much the more valuable.
Not withstanding the clear needs for and benefits that would be gained from such local drug delivery into the renal system, the ability to do so presents unique challenges as follows.
In one regard, the renal arteries extend from respective ostia along the abdominal aorta that are significantly spaced apart from each other circumferentially around the relatively very large aorta. Often, these renal artery ostia are also spaced from each other longitudinally along the aorta with relative superior and inferior locations. This presents a unique challenge to locally deliver drugs or other agents into the renal system on the whole, which requires both kidneys to be fed through these separate respective arteries via their uniquely positioned and substantially spaced apart ostia. This becomes particularly important where both kidneys may be equally at risk, or are equally compromised, during an invasive upstream procedure—or, of course, for any other indication where both kidneys require local drug delivery. Thus, an appropriate local renal delivery system for such indications would preferably be adapted to feed multiple renal arteries perfusing both kidneys.
In another regard, mere local delivery of an agent into the natural, physiologic blood flow path of the aorta upstream of the kidneys may provide some beneficial, localized renal delivery versus other systemic delivery methods, but various undesirable results still arise. In particular, the high flow aorta immediately washes much of the delivered agent beyond the intended renal artery ostia. This reduces the amount of agent actually perfusing the renal arteries with reduced efficacy, and thus also produces unwanted loss of the agent into other organs and tissues in the systemic circulation (with highest concentrations directly flowing into downstream circulation).
In still a further regard, various known types of tubular local delivery catheters, such as angiographic catheters, other “end-hole” catheters, or otherwise, may be positioned with their distal agent perfusion ports located within the renal arteries themselves for delivering agents there, such as via a percutaneous translumenal procedure via the femoral arteries (or from other access points such as brachial arteries, etc.). However, such a technique may also provide less than completely desirable results.
For example, such seating of the delivery catheter distal tip within a renal artery may be difficult to achieve from within the large diameter/high flow aorta, and may produce harmful intimal injury within the artery. Also, where multiple kidneys must be infused with agent, multiple renal arteries must be cannulated, either sequentially with a single delivery device, or simultaneously with multiple devices. This can become unnecessarily complicated and time consuming and further compound the risk of unwanted injury from the required catheter manipulation. Moreover, multiple dye injections may be required in order to locate the renal ostia for such catheter positioning, increasing the risks associated with contrast agents on kidney function (e.g. RCN)—the very organ system to be protected by the agent delivery system in the first place.
Still further, the renal arteries themselves, possibly including their ostia, may have pre-existing conditions that either prevent the ability to provide the required catheter seating, or that increase the risks associated with such mechanical intrusion. For example, the artery wall may be diseased or stenotic, such as due to atherosclerotic plaque, clot, dissection, or other injury or condition. Finally, among other additional considerations, much benefit would be provided from an efficacious and safe system and method for positioning these types of local agent delivery devices at the renal arteries through a common introducer or guide sheath shared with additional medical devices used for upstream interventions, such as angiography or guide catheters. In particular, to do so concurrently with multiple delivery catheters for simultaneous infusion of multiple renal arteries would further require a guide sheath of such significant dimensions that the preferred Seldinger vascular access technique would likely not be available, instead requiring the less desirable “cut-down” technique.
In addition to the various needs for locally delivering agents into branch arteries described above, much benefit may also be gained from simply locally enhancing blood perfusion into such branches, such as by increasing the blood pressure at their ostia. In particular, such enhancement would improve a number of medical conditions related to insufficient physiological perfusion into branch vessels, and in particular from an aorta and into its branch vessels such as the renal arteries.
Certain prior disclosures have provided surgical device assemblies and methods intended to enhance blood delivery into branch arteries extending from an aorta. For example, intra-aortic balloon pumps (IABPs) have been disclosed for use in diverting blood flow into certain branch arteries. One such technique involves placing an IABP in the abdominal aorta so that the balloon is situated slightly below (proximal to) the branch arteries. The balloon is selectively inflated and deflated in a counterpulsation mode (by reference to the physiologic pressure cycle) so that increased pressure distal to the balloon directs a greater portion of blood flow into principally the branch arteries in the region of their ostia. However, the flow to lower extremities downstream from such balloon system can be severely occluded during portions of this counterpulsing cycle. Moreover, such previously disclosed systems generally lack the ability to deliver drug or agent to the branch arteries while allowing continuous and substantial downstream perfusion sufficient to prevent unwanted ischemia.
It is further noted that, despite the renal risks described in relation to radiocontrast dye delivery, and in particular RCN, in certain circumstances local delivery of such dye or other diagnostic agents is indicated specifically for diagnosing the renal arteries themselves. For example, diagnosis and treatment of renal stenosis, such as due to atherosclerosis or dissection, may require dye injection into a subject renal artery. In such circumstances, enhancing the localization of the dye into the renal arteries may also be desirable. In one regard, without such localization larger volumes of dye may be required, and the dye lost into the downstream aortic flow may still be additive to impacting the kidney(s) as it circulates back there through the system. In another regard, an ability to locally deliver such dye into the renal artery from within the artery itself, such as by seating an angiography catheter there, may also be hindered in some limited circumstances by the same stenotic condition requiring the dye injection in the first place (as introduced above). Still further, patients may have stent-grafts that may prevent delivery catheter seating.
Accordingly, much benefit would result from providing the ability to effectively deliver agents from within a main artery, vessel, or lumen and locally into substantially only branch arteries, vessels, or lumens extending therefrom while allowing the passage of substantial flow (e.g. blood flow) and/or other medical devices through the main lumen past the branches. This is in particular the case with previously disclosed renal treatment and diagnostic devices and methods, which do not adequately provide for local delivery of agents into the renal system from a location within the aorta while allowing substantial blood flow continuously downstream past the renal ostia and/or while allowing distal medical device assemblies to be passed retrogradedly across the renal ostia for upstream use. Much benefit would be gained if agents, such as protective or therapeutic drugs or radiopaque contrast dye, could be delivered to one or both of the renal arteries in such a manner.
Several more recently disclosed advances have included local flow assemblies using tubular members of varied diameters that divide flow within an aorta adjacent to renal artery ostia into outer and inner flow paths substantially perfusing the renal artery ostia and downstream circulation, respectively. Such disclosures further include delivering fluid agent primarily into the outer flow path for substantially localized delivery into the renal artery ostia. These disclosed systems and methods represent exciting new developments toward localized diagnosis and treatment of pre-existing conditions associated with branch vessels from main vessels in general, and with respect to renal arteries extending from abdominal aortas in particular.
However, while these approaches in one regard provide benefit by removing the need to cannulate each renal artery of the bi-lateral renal system, substantial benefit would still be gained conversely from a device system and method that allows for direct bi-lateral renal artery infusion without the need to deploy flow diverters or isolators into the high-flow abdominal aorta. In one particular example, patients that suffer from abdominal aortic aneurysms may not be suitable for standard delivery systems with flow diverters or isolators that are sized for normal arteries. In another regard, direct renal artery infusion allows for reduced occlusion to downstream aortic blood flow, or conversely more downstream flow may be preserved. Still further, the ability to truly isolate drug to only the renal system, without the potential for downstream leaking or loss into the systemic circulation, may be maximized.
For renal cannulation and renal interventional device delivery in particular, current physician practice provides a limited number of shapes for the tip of a guiding catheter. If a specifically designed guiding catheter is available, the physician may be able to torque and manipulate the proximal end of the guiding catheter in order to steer the distal end of the guiding catheter into position to cannulate a target renal artery. The placement of the guiding catheter may cause some vessel trauma and damage due to large available sizes (5 French to 8 French), and conventional stiff distal tips and exposed edges without the use of a dilator. With the targeted renal artery cannulated, the physician may advance a guide wire into the renal artery to allow for placement and deployment of a guide wire based interventional device.
A second option that may be available to a physician is the use of a guiding catheter that is inserted and placed approximately near the targeted renal ostium. A guide wire is then advanced through the placed guiding catheter until the guide wire exits the guiding catheter roughly near the targeted renal ostium. Under fluoroscopic guidance, the physician manipulates the guide wire and tracks the wire into the renal arteries. This process may present a high risk of vessel perforation, dissection, and hematoma resulting from trauma as well as the release of emboli. Once the physician is able to track the guide wire to the target renal artery, the guide wire can then be used to further advance the guiding catheter, therefore allowing the exchange of interventional devices.
In the particular setting of interventional radiology and cardiology, numerous conditions exist that warrant placement of various intravascular devices into the renal arteries or veins. Such devices may include catheters and guide wires for diagnostic purposes, or systems for therapeutic or prophylactic applications such as drug infusion, monitoring/sampling, angioplasty and stenting, or embolic protection.
Current procedures to place such intravascular devices into the renal arteries or veins also involve the manipulation of guide wires and/or diagnostic or guiding catheters in the abdominal aorta/inferior vena cava in the area of the renal arteries/veins in order to gain access, and then following over (guide wires) or through (guiding catheters) these devices for placement of the intended interventional diagnostic, therapeutic, or prophylactic device. Such access procedures may require numerous expensive devices and be time consuming, increasing both the time of the procedure and its cost. As well, significant manipulation of various devices within the vasculature may lead to untoward clinical sequelae arising from trauma to the interior of the blood vessel walls or extensive x-ray or contrast media exposure.
Therefore, a need exists for a simpler, quicker, single device that may provide access to the renal vasculature for the delivery of interventional devices. There is in particular a need for such a device that may provide safe, quick, and easy access to both renals arteries or both renal veins simultaneously.
The particular need for rapid cannulation for percutaneous translumenal access to the renal system via the aorta is also illustrative of other procedures where rapid access to side-branch vessels from main vessels is required. These other situations also often require bilateral cannulation of multiple side branches from the main vessel. One such example is cannulation of right and left coronary artery systems from the aortic root, such as for coronary angiograms or other recanalization or stenting procedures. Another example may include cannulation of internal and external carotid arteries for certain procedures such as diagnosing or treating stroke, etc. In any event, while each particular anatomical location within the body is unique and requires special considerations in providing appropriate access systems and devices, certain general requirements and thus broad aspects of the system features may be common amongst such devices. For example, in cases where branches are to be cannulated via ostia located at unique positions along a substantially large vessel's wall (e.g. the aorta), conventional guide or delivery sheaths may be very difficult to find and seat into such discrete ostia from within the relatively expansive real estate of the main vessel.
Accordingly, there is also a need for an improved delivery device that is adapted to provide rapid, remote access for delivering interventional devices into a branch vessel extending at a unique location from a main vessel. There is in particular such a need for a bilateral delivery device assembly that is adapted to provide such access for interventional device delivery into multiple branch vessels extending at relatively unique locations from the main vessel.
Whereas various specific interventional procedures may benefit from such delivery systems, stenting and filtering methods are considered to reap particular benefit from an improved delivery modality. This in particular applies with respect to such procedures in the renal system.
Accordingly, there is a need for a stenting system and method that includes a stent assembly that cooperates with an improved delivery system for rapid cannulation and remote access and delivery of the stent assembly to at least one branch vessel extending from a main vessel. There is also a need for such stenting system and method that provides for at least bi-lateral cannulation and stent delivery into each of multiple branch vessels extending from a main vessel. Moreover, there is in particular a need for such stenting systems and methods just described that are in particular well suited and adapted for delivering stents into the renal arteries extending from renal ostia along an abdominal aorta wall.
In addition, there is also still a need for an embolic filtering system and method that includes an embolic filter assembly that cooperates with an improved delivery system for rapid cannulation and remote access and delivery of the filter assembly to at least one branch vessel extending from a main vessel. There is also a need for such filtering system and method that provides for at least bi-lateral cannulation and filter delivery into each of multiple branch vessels extending from a main vessel. Moreover, there is in particular a need for such filtering systems and methods just described that are in particular well suited and adapted for delivering embolic filters into the renal arteries extending from renal ostia along an abdominal aorta wall.
As will be seen below, certain of the problems and needs left unmet by prior disclosures and efforts are addressed by one or more of the various aspects, modes, embodiments, variations, or features of the current invention.